LoginActivity with persistant AsyncTasks

LoginActivity.java

package com.vokal.petcheck;

import android.app.Activity;
import android.app.AlertDialog;
import android.app.ProgressDialog;
import android.content.Context;
import android.content.DialogInterface;
import android.content.Intent;
import android.os.AsyncTask;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.view.Window;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;

import com.vokal.petcheck.constants.Constants;
import com.vokal.petcheck.walk.User;

import java.util.ArrayList;

public class LoginActivity extends Activity
{
    private static final String TAG = "LoginActivity";

    private static final int SECURITY_ACTIVITY = 0;

    private Button mLogin;
    private Button mForgotPassword;
    private EditText mUsername;
    private EditText mPassword;
    private ProgressDialog mDialog;

    private LoginTask mLoginTask;
    private ForgotPasswordLaunchTask mForgotTask;

    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState)
    {
        super.onCreate(savedInstanceState);
        
        requestWindowFeature(Window.FEATURE_NO_TITLE);

        setContentView(R.layout.login_activity);

        ArrayList<Object> retained = (ArrayList<Object>) getLastNonConfigurationInstance();
        
        if (retained != null) {
            mLoginTask = (LoginTask) retained.get(0);
            mForgotTask = (ForgotPasswordLaunchTask) retained.get(1);
        }

        if (mLoginTask != null) {
            if (!mLoginTask.getStatus().equals(AsyncTask.Status.FINISHED)) {
                mLoginTask.setContext(this);
                mDialog = ProgressDialog.show(LoginActivity.this, 
                    "Loading", "Logging In");
            }
        }

        if (mForgotTask != null) {
            if (!mForgotTask.getStatus().equals(AsyncTask.Status.FINISHED)) {
                mForgotTask.setContext(this);
                mDialog = ProgressDialog.show(LoginActivity.this, 
                    "Loading", "Retrieving Security Question");
            }
        }

        mLogin          = (Button) findViewById(R.id.login_submit);
        mForgotPassword = (Button) findViewById(R.id.login_forgot);
        mUsername       = (EditText) findViewById(R.id.login_username);
        mPassword       = (EditText) findViewById(R.id.login_password);
        
        mLogin.setOnClickListener(mLoginListener);
        mForgotPassword.setOnClickListener(mLoginListener);

    }

    @Override
    public void onPause() {
        super.onPause();
        if (mDialog != null) {
            mDialog.dismiss();
        }
    }

    @Override
    public void onStop() {
        super.onStop();
        if (mDialog != null) {
            mDialog.dismiss();
        }
    }

    @Override
    public void onDestroy() {
        super.onDestroy();
        if (mDialog != null) {
            mDialog.dismiss();
        }
    }

    @Override 
    public Object onRetainNonConfigurationInstance() {
        ArrayList<Object> retainedObjects = new ArrayList<Object>();
        retainedObjects.add(mLoginTask);
        retainedObjects.add(mForgotTask);
        return retainedObjects;
    }
    
    public void onActivityResult(int aRequestCode, int aResultCode, Intent aIntent) {
        if (aRequestCode == SECURITY_ACTIVITY) {
            if (aResultCode == RESULT_OK) {
                launchWelcomeScreen();
            }
        }
    }

    public void checkLogin() {
        String username = (mUsername.getText()).toString();
        String password = (mPassword.getText()).toString();

        boolean usernameEmpty = username.equals("");
        boolean passwordEmpty = password.equals("");

        if(!(usernameEmpty) &&!(passwordEmpty)) {
            mLoginTask = new LoginTask();
            mLoginTask.setContext(this);
            mLoginTask.execute(username, password);
        } else if (usernameEmpty && passwordEmpty) {
            Toast.makeText(LoginActivity.this,
                R.string.login_both_empty, Toast.LENGTH_SHORT).show();
        } else if (usernameEmpty) {
            Toast.makeText(LoginActivity.this,
                R.string.login_username_empty, Toast.LENGTH_SHORT).show();
        } else if (passwordEmpty) {
            Toast.makeText(LoginActivity.this,
                R.string.login_password_empty, Toast.LENGTH_SHORT).show();
        }
    }

    public void forgotPressed() {
        final EditText usernameField = new EditText(LoginActivity.this);
        usernameField.setHint("username");
        new AlertDialog.Builder(LoginActivity.this)
            .setTitle("Enter Username")
            .setView(usernameField)
            .setPositiveButton("OK", 
                new DialogInterface.OnClickListener() {
                    public void onClick(DialogInterface aDialog, int aWhich) {
                        String username = usernameField.getText().toString();
                        if (!username.equals("")) {
                            mForgotTask = new ForgotPasswordLaunchTask();
                            mForgotTask.setContext(LoginActivity.this);
                            mForgotTask.execute(username);
                        }
                    }
                })
            .setNegativeButton("Cancel", null)
            .show();
    }

    public View.OnClickListener mLoginListener = new View.OnClickListener() {
        public void onClick(View aView) {
            switch(aView.getId()) {
                case R.id.login_submit:
                    checkLogin();
                    break;
                case R.id.login_forgot:
                    forgotPressed();
                    break;
                default:
                    break;
            }
        }
    };

    public void launchWelcomeScreen() {
        mUsername.setText("");
        mPassword.setText("");
        
        Intent i = new Intent();
        i.setClass(LoginActivity.this, WelcomeActivity.class);
        startActivity(i);
    }

    public class LoginTask extends AsyncTask<String, Void, Boolean> {
        private LoginActivity mContext;

        public void setContext(LoginActivity aContext) {
            mContext = aContext;
        }

        public void onPreExecute() { 
            LoginActivity.this.mDialog = ProgressDialog.show(LoginActivity.this, 
                "Loading", "Logging In");
        }

        public Boolean doInBackground(String... aParams) {
            boolean result = false;

            if (!isCancelled()) {
                result = User.getLogin(aParams[0], aParams[1]);
            }

            return result;
        }

        public void onPostExecute(Boolean aResult) {
            if (!isCancelled()) {
                mContext.clearDialog();
                if (aResult == true) {
                    launchWelcomeScreen();
                } else {
                    getWrongLoginDialog(LoginActivity.this).show();
                }
            }
        }
    }

    public class ForgotPasswordLaunchTask extends AsyncTask<String, Void, String> {
        private String mUsername;
        private LoginActivity mContext;

        public void setContext(LoginActivity aContext) {
            mContext = aContext;
        }

        public void onPreExecute() {
            mDialog = ProgressDialog.show(LoginActivity.this,
                "Loading", "Retrieving Security Question");
        }

        public String doInBackground(String... aParams) {
            String result = "";

            if (!isCancelled()) {
                mUsername = aParams[0];
                result = User.getSecurityQuestion(aParams[0]);
            }

            return result;
        }

        public void onPostExecute(String aResult) {
            
            if (!isCancelled()) {
                mContext.clearDialog();
                if (aResult != null && !aResult.equals("")) {
                    Intent i = new Intent();
                    i.setClass(LoginActivity.this, SecurityQuestionActivity.class);
                    i.putExtra(Constants.PARAM_USERNAME, mUsername);
                    i.putExtra(Constants.SECURITY_QUESTION, aResult);
                    startActivityForResult(i, SECURITY_ACTIVITY);
                } else {
                    getWrongLoginDialog(LoginActivity.this).show();
                }
            }
        }
    }

    public void clearDialog() {
        Log.d(TAG, "Clearing Dialog");
        mDialog.dismiss();
    }

    private AlertDialog.Builder getWrongLoginDialog(Context aContext) {
        return new AlertDialog.Builder(aContext)
            .setIcon(android.R.drawable.ic_dialog_alert)
            .setTitle(aContext.getString(R.string.wrong_password))
            .setMessage(aContext.getString(R.string.wrong_password_dialog))
            .setPositiveButton("OK", null);
    }

}